<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>defaults</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const defaults = (obj, ...defs) =>
            Object.assign({}, obj, ...defs.reverse(), obj);
        console.log(defaults({ a: 1 }, { b: 2 }, { b: 6 }, { a: 3 }));
    </script>
</body>

</html>